Senior Software Engineer, Backend (Payments)

Location: Remote UK; most roles can be performed remotely within the country of employment, with occasional in-person office work or onboarding.

Base pay: £101,000–£149,000 per year.

Company

Affirm develops consumer payment and buy-now-pay-later products designed to provide transparent, predictable credit without hidden fees or compounding interest.

What you will do

• Break larger projects into tasks, deliver them in phases, and collaborate with stakeholders to ensure timely delivery.
• Partner with product management, design, and analytics to evaluate ideas, technical constraints, risks, and trade-offs.
• Design, develop, launch, and operate backend systems and APIs for payment flows handling billions of dollars annually.
• Create and monitor metrics, support service availability, escalate incidents, and participate in on-call and operational work.
• Contribute to team growth through development activities and participation in interviews.

Requirements

• 1.5+ years of total software engineering experience.
• Experience with JavaScript and TypeScript.
• Experience designing, developing, and launching backend systems, with proficiency in Python or Kotlin.
• Familiarity with distributed-systems fundamentals and technologies including AWS, MySQL, and Kubernetes.
• Experience designing, developing, and launching APIs at scale using Python or Kotlin.
• Ability to turn business scenarios into solutions spanning multiple software components and write clear, well-tested, extensible code.
• Comfort navigating large codebases, debugging other engineers’ code, and providing code-review feedback.
• Proactive ownership of professional growth and strong verbal and written communication for collaboration with a global engineering team.

Culture & Benefits

• Remote-first work model with flexibility within the country of employment; all new hires attend an in-person onboarding experience.
• 100% subsidized medical coverage, including coverage for employees’ dependents, plus dental and vision benefits.
• Monthly stipends for technology, health, and wellness expenses.
• Flexible time off and generous holiday calendars.
• Employee stock purchase plan with discounted Affirm shares.
• Visa sponsorship is not available for this position.

Hiring process

• Inclusive interview accommodations are available for candidates with disabilities upon request.